1. Field of the Invention
The present invention relates to telecommunications services and, more particularly, to a method and apparatus for dialing calls.
2. Description of Related Art
Recent advances in telecommunications systems have enabled a wide array of special services to be made available to subscribers. One such service is abbreviated dialing, which allows a subscriber to reach a party by dialing less than the entire telephone number of that party. For many years now, private branch exchange (PBX) systems have provided users with an abbreviated dialing function, in which each PBX terminal is assigned an extension number, and a user at any terminal may place a call to any other terminal within the system by simply dialing the extension of that other terminal.
Typically, a public telephone company may assign to a PBX system a group of telephone numbers, all of which might have a common area code and prefix (e.g., NPA-NXX or NPA-NX, where N is any digit 2–9) and each of which may then have a distinct suffix or “extension” (e.g., XXXX or XXXXX, where X is any digit 0–9), which comprises the digits in the telephone number following the area code and prefix. The area code (NPA) may serve to designate a particular toll center or calling area, and the prefix (NXX or NX) may serve to designate a particular telephone company central office. (In recent years, with the growth of “local number portability,” the direct relationship between prefix and central office has faded to some extent, yet the relationship still generally exists.)
Conveniently, the PBX may in turn assign each of the telephone numbers to a respective one of the terminals in the PBX system. Therefore, in order to call one of the terminals from a telephone outside of the PBX system, a person can dial the area code, prefix and extension of the terminal, and the call will be routed by the telephone company to the PBX and in turn to the terminal. Further, in order to call one of the terminals from another telephone within the PBX system, a person can simply dial the extension of the terminal, and the PBX will route the call to the terminal.